SAFETY START

摘要

A starting circuit for an induction motor is provided whereby a stationary rotor flux is established then a stored charge supplied to a motor winding i n order to provide a starting torque. Before applying a mains power supply to the motor after the starting torque has been applied, a back EMF is sensed, directly or indirectly, to provide an indication that the rotor is turning before the mains supply is connected to the motor. This provides a reliable and simple method for ensuring that a mains supply may be safety connected t o the motor.